Fluid filters must be periodically cleaned and/or replaced to prevent undue buildup of dirt and particulate matter which would adversely affect proper operation. For example, pulse-jet air cleaners are typically used in applications requiring treatment of large volumes of air. Cleaning is accomplished by periodically pulsing air through the filters in a direction opposite to the normal airflow direction to effect backflushing during operation of the system and thus extend the recommended service interval between removal and replacement of the filters. For example, U.S. Pat. No. 4,331,459 to Donaldson Company, the assignee hereof, shows a representative self-cleaning pulsed air cleaner.
Such pulse-jet air cleaners generally include a reservoir or tank of compressed air having an outlet connected by a discharge pipe to a diaphragm valve and onto a nozzle or orifice positioned to direct the air against the filter to effect cleaning. The diaphragm valve is normally closed, but is controlled by a pilot valve to open momentarily and release a large volume of air at high velocity which is directed toward a filter opening, thereby generating the necessary cleaning energy. The air tank is charged by a compressor.
The pulse-jet air cleaners of the prior art have been satisfactory for most industrial applications, but are not suited for certain high-performance industrial applications and vehicular applications requiring maximum cleaning energy in minimum space. More critical design constraints are present in high-performance applications. For example, some vehicular applications can require up to twenty times the cleaner size reduction as compared to industrial pulse-jet air cleaners. In addition, the media velocities in vehicular air cleaners are usually higher, which in turn requires higher cleaning energy, but the available compressed air supply is likely to be more limited than that available in industrial applications. The prior pulse-jet air cleaners tend to be relatively bulky, expensive, difficult to assemble, and inefficient due to flow losses resulting from their construction. There are thus several drawbacks to the use of the prior pulse-jet air cleaners in high performance applications.
A need has thus arisen for an improved pulse-jet air cleaner which is suitable for use in either industrial or vehicular applications requiring higher performance, but which does not have the bulk, limited cleaning energy and other drawbacks associated with the prior art.